72 HAUPT — METHODS OF IMPROVING OCEAN BARS. [May 3, 



jetties, one somewhat longer than the other, its curved shape pos- 

 sibly making up in part for the lack of length in its mate. The first 

 of these jetties — the north one — is composed of two parts, one of 

 which is a natural bank extending from St. Joseph's Island to the 

 inner end of the breakwater, a distance of about 1700 feet." As 

 there is no " natural bank" across this 1700 feet of tidal opening, 

 where the depths are from five and a quarter to four and three- 

 quarters and two feet at mean low water and which opening is a 

 part of the design to admit the full tidal enegry, and as all of the 

 inner end of the so-called jetty to a point 4000 feet from the island 

 is below water surface, some of it as much as fifteen feet, it is diffi- 

 cult to accept the statement that it is part of the jetty relied upon to 

 control effectively the ebb currents or even to arrest sand, which does 

 undoubtedly enter the channel through the gaps to the detriment 

 of the work (see Proceedings of American Philosophical Soci- 

 ety, Vol. 38, Plate VII). 



But the author, not appreciating fully the important function of 

 arresting this drift, adds that " the trend of the currents is such that 

 no artificial structure is needed here." Yet the Government Board 

 recommends in its proposed plan to close this opening by a sill some 

 three or more feet high. Why should it do so if not needed to con- 

 trol the currents, or if, as the author asserts, the sand is drifting in 

 through this opening, why should it not be needed to arrest this 

 movement ? 



The report then stated that " for a further distance east of 4650 

 feet we have in the breakwater itself a more or less complete actual 

 jetty, with a little foundation beyond this." 



How much is " more" and how much "less" does not appear ; 

 so that from the author's view it would seem the north jetty consists 

 of a natural bank for 1700 feet and a more or less completed actual 

 jetty of 4650 feet, a total structure of 6350 feet, giving the impres- 

 sion to one ignorant of the facts that there is a retaining wall of that 

 length which controls the currents, whereas of the reaction break- 

 water, or so-called " north jetty," less than 1500 feet reach above 

 high water, and hence for only about twenty per cent, of this entire 

 distance are the currents under the full control of the structure. 



The alleged south jetty, according to the report, is built up in a 

 similarly ideal manner, as follows : 



"Opposing this and forming the south jetty we have, first, the 

 reveted head of Mustang Island and the old Nelson jetty, extend- 



